Technical Field
The present disclosure relates generally to computer-aided design, and more specifically to inter-relating a three-dimensional (3-D) model and two-dimensional (2-D) raster images, such as photographs.
Background Information
To better manage the complexities of modern structures, engineers, architects, and other professionals often turn to computer-aided design. Using a modeling application, they may create a 3-D model of the structure. In the 3-D model, the structure may be represented by a collection of individual elements, for example, vector elements (e.g., lines, polygons, etc.), that represent important features, such as boundaries, openings, partitions and the like. Depending on the particular 3-D model, the level of detail provided by the individual elements varies. The greater the level of detail, typically the greater the time and cost required to construct the 3-D model. Producing extremely detailed models may be time or cost prohibitive in some situations. Further, even when a 3-D model is very detailed, it may not accurately reflect real-world conditions. For example, when a 3-D model is used to build a structure, the “as-built” condition of the structure may be significantly different than the model. During construction, on-site changes are often made that are not propagated back to the 3-D model. Further, after initial construction, various repairs and renovations may be made that similarly are not propagated back to the 3-D model.
Engineers, architects, and other professionals also utilize 2-D raster images (e.g., photographs) when trying to better understand structures. In a 2-D raster image, information is generally displayed as a grid of discrete points (pixels) that each have a corresponding color value. A 2-D raster image may be characterized by a width and a height in pixels and by a color depth that indicates a number of colors each pixel may represent. 2-D raster images are generally simple to capture, for example, by taking a digital photograph, and can contain extensive amounts of information. However, the information contained in 2-D raster images is generally difficult to utilize. While features may be shown, it is typically difficult to determine the precise position of these features in relation to other features, and the overall geometry of the structure.
In some cases, both a 3-D model and 2-D raster images may be available for the same structure. However, rather than complement each other, with existing techniques they typically compounded other's deficiencies. Accordingly, there is a need for improved techniques that permit effective use of 3-D models and 2-D raster images together.